In my early botanising days I was keen to see this plant initially introduced from South East Asia. It wasn't anywhere near as common as it is now and every time I came across a particularly tall version of Heracleum sphondylium (Hogweed) I wondered whether or not it was the Giant Hogweed (H. mantegazzianum). Of course as soon as I was shown the real thing I realised there was no confusing the two plants. The plant in the photo is not a particularly large one but the individual flower heads are about a metre in diameter. It is a spectacular plant with a very bad reputation. The sap in the presence of light causes a photochemical reaction with human skin giving rise to severe ulceration and burns. Children have sometimes cut the stems and used them as pea-shooters with terrible consequences.

It is now often seen by the side of roads and rivers. If you want to see a forest of these plants, travel as a passenger south on the M6 over the Thelwall viaduct and at the top take a quick peek towards the River bank below. In June and July there are about 20 or 30 of these plants in full flower in a fairly inaccessible spot.

H. mantegazianum has naturalised in most of England but not much of mid and west Wales. In Scotland it can be found mostly in the central lowland and the coast near Inverness but has not reached the far north. In Ireland it is mostly found in the north only dotted here and there in the south.

Banks of ditch on Sealand Retail park Chester 30th June 2005

Added on 5th July 2005, updated 6th February 2009, updated 6th April 2010